Over one-quarter of all American children are overweight or obese. This study was designed to determine why some children become obese and others do not. The major aims of the study are: 1. To determine if children who become obese have lower energy expenditures (adjusted for fat free mass) in comparison with children who do not become obese. 2. To determine energy requirements for children based on their total energy expenditure. The study included measurement of the following variables: total energy expenditure using doubly labeled water, resting metabolic rate, body composition using dual energy x-ray absorptiometry, anthropometry, and dietary intake using the multiple-pass 24-hour recall. The Vermont portion of the study is part of a larger longitudinal cohort study based at the University of Alabama in Birmingham. All Vermont children have been tested. The data are now being compiled and prepared for statistical analysis. The Vermont data will be combined with data from both Caucasian and African-American children residing in Birmingham, Alabama and the surrounding area.